The present invention relates to a waterproof deck and to a method of making a waterproof deck and especially to an apparatus and method which prevents the accumulation of water between a concrete floor and the waterproof membrane on the subfloor.
In the past, it has been common to make concrete decks for apartment buildings and the like in which the deck is placed between walls on three sides and open on the fourth side. Decks are typically made with joists mounted between the walls and a plywood subfloor attached to the joists. Typically, a waterproof membrane, such as building paper, coated felt roofing material, roofing asphalt or the like, is used to coat a subfloor and then a concrete flooring is poured on top of the waterproof coating to form the floor. A drip edge is commonly used along the open edge of the deck. The deck may have a slight slope so that rain or water falling onto the deck drains off the concrete and over the drip edge. Prior art decks of this type have tended to have the subflooring and joist rot out in a fairly short period of time as a result of the accumulation of moisture from the concrete below the concrete flooring. In a typical deck of this type, flashing has been placed around the deck along the walls adjacent the attached deck and a waterproof sheathing has been placed on the subfloor so that water accumulating from the concrete floor tends to accumulate under the concrete floor and tends to get through or around the waterproof sheathing placed on the subfloor. This happens because the sheathing is sometimes not fully watertight and at other times tends to get damaged, such as with minute holes that allow the seepage of water therethrough. The water that accumulates under the concrete floor has no where to run off and thereby tends to accumulate and build up until any leak or spacing around the flashing allows the seepage to make its way to the wooden subfloor and joists which then very quickly rot out and causes extensive damage.
For efficient water shedding at the deck and roof edges of a building, a metal drip edge is usually installed. These have various shapes and may be formed from 26 gauge galvanized steel. They extend back about three inches from the deck edge and are bent downward over the edge and may have an outwardly bend or lip at the edge of the metal to cause the water to drip free of the underlying deck or joist construction. It has also been common in the past to use T-bar edge materials extending over a roof edge especially in flat or built-up roofs where the metal portion of the T-bar extends over the roof sheathing and also has raised edges to act as a metal gravel stop for containing gravel covering the built-up roof. Built-up roofs commonly use sheathing paper or felt as well as corner flashing to protect the surfaces.
The present invention is directed towards a system for preventing the damage by the rotting of concete floor decks wooden components commonly used in multi-story buildings and the like and provide an apparatus and method for preventing accumulation of the water and moisture over and beneath the concrete surface.
Prior U.S. patents that have been found of interest to the present invention include the O'Riordain, U.S. Pat. No. 4,274,238, for a roof structure providing for efficient drainage of flat roofs and includes a drainage board above a water barrier layer and below a thermal insulation layer so that water falling on a flat roof passes through the protective layer of gravel through the abutting joints of a thermal insulation layer and through the drainage board and to conventional water gulleys and downpipes. In the VanWagoner, U.S. Pat. No. 4,719,713, a thermally efficient protected membrane roofing system is provided which also includes a drainage and insulation board and a vapor barrier. The seams between adjacent roofing panels is covered with a waterproof but vapor permeable tape and the panels are covered with a protective layer. The Paquette, U.S. Pat. No. 4,937,990, shows a ventilation system for roofs which makes the drying of roof insulation easier. The Paquette et al. U.S. Pat. No. 5,144,782, similarly has a double level drainage system for flat roofs so that water which may collect between the upper and lower membranes of flat, horizontal, or slightly sloped roofs upon perforation of the upper membrane. The insulated panels located between the two membranes are provided at both their upper and lower faces with a network of intersecting grooves and a lower drain is sealed to and opens through the lower membrane to drain any water that has seeped thereinto. The Carter, U.S. Pat. No. 3,434,260, has a series of separately formed gutters underlying the joints between adjacent tiles so that water penetrating the joints is drained by the underlying gutter to the next floor tile and onto the aligned next lower channel. The LaRoche et al., U.S. Pat. No. 4,663,894, is a flexible gutter attached beneath expansion joints for draining off water seeping between the expansion joints at the abutment of interconnecting concrete surfaces. The Riley et al., U.S. Pat. No. 4,658,554, is a protected membrane roof system for high traffic roof areas having a waterproof membrane attached to the roof deck and extruded panels of closed cell polystyrene foam mounted on top of the membrane to protect the membrane from thermal cycling, ultraviolet rays, and physical damage and is resistant to water. Concrete panels are laid directly on top of the polystyrene foam. In the Ager, U.S. Pat. No. 2,646,011, a roof gutter is provided for flat roofs which forms a trough section and spillway with specially formed sheet metal.
The present invention provides a simplified disposal of accumulated moisture through a concrete floor to prevent the accumulation of moisture between the floor and the waterproof membrane covering the subfloor so that the cost of building the decks does not increase substantially while preventing subfloors, joists, and the like from rotting out. The problem results because concrete does not provide a total barrier to the passage of moisture and water tends to accumulate beneath the concrete surface where the concrete surface is frequently covered with water. Generally, building codes require that concrete floors always have a moisture barrier placed over any wooden surfaces to which the concrete is to be placed upon. This, however, has not been effective in preventing the wood structure which supports a concrete deck from being damaged by the accumulation of moisture which finds its way through or around the waterproof membrane.